MUSEN: Aggregatable Key-Evolving Verifiable Random Functions and Applications

Bernardo David; Rafael Dowsley; Anders Konring; Mario Larangeira

Paper 2024/628

MUSEN: Aggregatable Key-Evolving Verifiable Random Functions and Applications

Bernardo David, IT University of Copenhagen

Rafael Dowsley, Monash University

Anders Konring, Espresso Systems

Mario Larangeira, Tokyo Institute of Technology, IOG

Abstract

A Verifiable Random Function (VRF) can be evaluated on an input by a prover who holds a secret key, generating a pseudorandom output and a proof of output validity that can be verified using the corresponding public key. VRFs are a central building block of committee election mechanisms that sample parties to execute tasks in cryptographic protocols, e.g. generating blocks in a Proof-of-Stake (PoS) blockchain or executing a round of MPC protocols. We propose the notion, and a matching construction, of an Aggregatable Key-Evolving VRF (A-KE-VRF) with the following extra properties: 1. Aggregation: combining proofs for several VRF evaluations of different inputs under different secret keys into a single constant size proof; 2. Key-Evolving: preventing adversaries who corrupt a party (learning their secret key) from ``forging'' proofs of past VRF evaluations. As an immediate application, we improve on the block size of PoS blockchains and on the efficiency of Proofs of Proof-of-Stake (PoPoS). Furthermore, the A-KE-VRF notion allows us to construct Encryption to the Future (EtF) and Authentication from the Past (AfP) schemes with a Key-Evolving property, which provides forward security. An EtF scheme allows for sending a message to a party who is randomly selected to execute a role in the future, while an AfP scheme allows for this party to authenticate their messages as coming from a past execution of this role. These primitives are essential for realizing the YOSO MPC Framework (CRYPTO'21).

Note: Added comparison to recent and independent related works.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Published elsewhere. Major revision. SCN 2024
Keywords: Verifiable Random Functions YOSO MPC Encryption to the Future Proof-of-Stake Blockchain
Contact author(s): bernardo @ bmdavid com
rafael dowsley @ monash edu
anders @ espressosys com
mario @ c titech ac jp
History: 2024-07-08: last of 3 revisions; 2024-04-24: received; See all versions
Short URL: https://ia.cr/2024/628
License: CC BY

BibTeX

@misc{cryptoeprint:2024/628,
      author = {Bernardo David and Rafael Dowsley and Anders Konring and Mario Larangeira},
      title = {{MUSEN}: Aggregatable Key-Evolving Verifiable Random Functions and Applications},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/628},
      year = {2024},
      url = {https://eprint.iacr.org/2024/628}
}